Conventionally, a vehicle door locking device is known as disclosed in Japanese Patent Application Publication No. 2002-89109 and WO 2012/120790A1. Specifically, as illustrated in FIG. 8, a locking device disclosed in Japanese Patent Application Publication No. 2002-89109 includes a lock arm 82 and a rotating member 83 provided on an attachment plate 81 so as to be rotatable. The rotating member 83 rotates when an engagement pin 84 provided on a door enters an engagement groove 83a of the rotating member 83. The lock arm 82 can be positioned at a lock position at which a distal end thereof makes contact with a distal end surface 83b of the rotating member 83 to lock the rotating member 83 and a unlock position at which the distal end thereof is separated from the distal end surface 83b of the rotating member 83 to allow rotation of the rotating member 83. A lock switching pin 85 is provided on a lower side of the lock arm 82 so as to advance or retract. With movement of the lock switching pin 85, the lock arm 82 moves to the lock position or the unlock position. When the lock arm 82 is at the lock position, since rotation of the rotating member 83 is inhibited, it is not possible to move the door. On the other hand, when the lock arm 82 is at the unlock position, an opening/closing operation of the door is allowed.
A locking device disclosed in WO 2012/120790A1 is switched from an unlock state to a lock state based on a velocity signal of a vehicle. That is, the locking device is switched to the lock state when the vehicle starts moving and the velocity thereof reaches a predetermined velocity rather than switching the locking device to the lock state when the door is closed. Thus, even when an object is caught in the door, as long as the vehicle is in a stopped state, it is possible to open the door and to easily remove the caught object.
In the locking device disclosed in Japanese Patent Application Publication No. 2002-89109, when the door is at a closed position, the rotation of the rotating member 83 is restricted by the lock arm 82. Thus, when an object or the like is caught in the door, it is not possible to operate the door in an opening direction. Thus, it is difficult to remove the object or the like caught in the door.
On the other hand, in. WO 2012/120790A1, since the door is not locked until the velocity of a train reaches a predetermined velocity, although it is possible to remove the object or the like caught in the door, the door may be opened unexpectedly.